Electronic equipment normally has a given range of acceptable environmental conditions, such as temperature and humidity, within which the equipment will properly function. These ranges are determined by the design parameters of the components of the electronic equipment and the manufacturing techniques used to assemble the components into a finished product. When the environmental conditions within a housing of the electronic equipment are outside these acceptable ranges, the equipment may malfunction and is susceptible to damage. Further, the lighter and smaller electronic apparatus become, the more susceptible they are to the adverse effects of climatic conditions because they are more likely to be used in environments where climatic conditions are not controlled.
To prevent malfunctioning of or damage to electronic equipment, equipment designers often take steps to control the environmental conditions within the housing of the electrical equipment. Such devices as fans for cooling the electronic components or dehumidifiers for extracting moisture from the air within the housing may be provided within the housing to control the conditions in the housing. However, in many pieces of electronic apparatus, especially in consumer electronics such as hand held video cassette recorders, size and weight constraints prevent the inclusion of such devices within the housing of the electronic equipment.
In cases where it is impractical to control the environment within the electronic equipment housing, equipment designers often provide sensors for determining whether environmental conditions are outside of acceptable ranges. These sensors are electronically coupled with shut-off switches that prevent the operation of the electronic equipment when environmental conditions are unacceptable. Such sensors and switches may also be employed in conjunction with devices designed to control the environmental conditions within the housing. These sensors and interlocks prevent improper operation of and damage to the electronic equipment.
The above-described problems are particularly acute in the field of video tape camera recorders. Therefore, the present invention is particularly suited to use with video cameras and will be discussed below as it applies to such cameras. However, the following discussion of this application of the present invention should not be construed as limiting the present invention to use with video cameras. As examples, electronic equipment such as portable computers and portable audio tape players and recorders may also be susceptible to problems that can be solved by devices that come within the broader scope of the present invention.
Video tape camera recorders are often portable and are thus taken from the relatively controlled environment of the home for use out-of-doors and in other conditions that may be hostile to the camera components. For example, if such a camera is removed from the warm interior of a car into a cold environment, condensation may form on the inside of the camera.
Because these video cameras are designed to be hand-held and thus must be small in size and lightweight, fans and de-humidifiers may not be included within the housings thereof. Video camera designers thus employ sensors to determine, for example, the humidity within the housing of the video camera. These sensors generally comprise a resister whose resistance varies in a known fashion with different levels of humidity. By monitoring the voltage across and/or the current passing through such a resister, the humidity level within the video camera can be monitored. When the humidity level thus measured exceeds a predetermined value, a switch is triggered which inhibits the operation of the video camera. A message may also be displayed on the camera's monitor indicating that the camera is wet.
While this approach is acceptable at protecting the video camera from damage, the video camera is rendered inoperative for as long as the humidity within the housing exceeds the predetermined amount. During this drying time, the video camera operator may miss the opportunity to record important, transitory events.
As additional background, it should be noted that designers of video cameras do not take into consideration, or make design decisions in support of, any attempts by third parties to design products for the care, maintenance, and improved operation of these cameras. A dichotomy thus exists between camera designers who design cameras to be light-weight, compact, and inexpensive to manufacture and third parties whose design goals are to optimize the performance of these cameras.